Background Critically ill children admitted to a Paediatric Intensive Care Unit (PICU) experience pain and distress. The COMFORT Behaviour (COMFORT B) Scale is a widely used pain and distress assessment scale, validated in children less than 3 years. Minimal studies assess whether the scale is sensitive to detect changes in pain and sedation levels after a treatment intervention is administered. Sensitivity to change, defined as the ability of a measure to detect statistically significant changes after pain treatment, is a relevant psychometric property for pain instruments. With many PICUs now making decisions about analgesia and sedation management based on COMFORT B assessments, it is crucial that these issues are rigorously explored. The aim of the study is to determine if the COMFORT B Scale is sensitive to change.

Methods The study is a prospective observational study. Admissions to the PICU of children less than 3 years, who had a COMFORT B score indicating pain or under sedation were included. Re-administration of the COMFORT B scale within 2 h of an intervention was performed to assess sensitivity to change.

Results An initial pilot study found excellent interrater reliability in 97 assessments performed by 2 nurses blinded to each other’s scores. Consequently, single nurse paired assessments were completed before and after an intervention and sensitivity to change was established.

Conclusions The study identifies that the COMFORT B scale is sensitive to detect change following pharmacological and non pharmacological interventions. Thus proposing the COMFORT B scale effectively guides pain and sedation management.